Speed control device for movable grids



Jan. 2, 1934.

C. J. LARSEN 1,941,989

SPEED CONTROL DEVICE FOR MOVABLE GRIDS Filed Oct. 16, 1931 'IHHHHIHI mumllh il f 'mdwww# vvvv - 0 INVENTOR Patented Jan. 2, 1934 'Unirse srarss Lenses SBEED CONTRQL DEVECE FOR MOVABLE GREDS Carl .1. Larsen, Qrange, N. J., assigner to Wappler Electric Company, Inc., a corporatien of New York Application c'lobcr 16,

7 Claims.

My invention relates to timing devices for movable grids of the soi-called Bucky type utiliZed in radiography for suppressing the passage ci secondary X-rays which tend to fog a sensi- Vtized nlm during exposure of an object to X- rays.

- Such devices are employed by the Roentgenologist in the field of exposure between the sensitized nlm and the object to be radiographed. The primary X-rays in passing through the body or" a patient cause slant or secondary rays to emanate in various angular directions from the bones and tissues ci the patient, which if not in some manner suppressed will also strike the i I lm resulting in a blurred picture. By providing a secondary grid composed of alternate strips of material pervious and impervious to X-rays which moves across the field of exposure between the object and film, these secondary rays are i prevented from striking the nlm.

This grid must necessarily be started in motion before energization o the X-ray tube and must not cease its movement until deenergization y thereof in order to completely prevent the sec- .25,

'l sion ofV a timing mechanism, operably connected to a grid, employing a plurality of yieldable chambers containing a iluid and in which the rate of flow of the fluid from one oi these yieldable chambersto the other may be adjusted to vary the speed of movement of the grid.

Another object of my invention is the provision of a timing mechanism, operably connected to a grid, in which a plurality of yieldable chambers containing a nuid are employed and one of these chambers is compressed and the other expanded with the iuid owing from one chamber to the other when the grid is moved in either direction or" its movement and the rate of now vof this r'luid may be regulated to vary the speed `-ture and highly eflcient in its operation and in (Cl. ,2W-34) Serial No. 569,224

which the speed of movement of the grid may be varied with minute exactitude.

Still further objects of my invention will become apparent to those skilled in the art by reference to the accompanying drawing wherein: e@

Figure 1 is a plan view partly in section of my timing mechanism showing the grid in one extremity or" its reciprocatory movement;

lFigure 2 is a partial plan view partly in section of Vmy timing mechanism showing the grid'v in 65 the other extremity of reciprocatory movement,

and

Figure 3 is a sectional View taken on the line II-III of Fig. 1.

Referring now to the drawing in detail I have '1Q shown a suitable support 5 such as a cassette tray for holding sensitized films or a portion of a radiographic table'eitlier of which are well known in theart. Suitable rollers 6 are carried by this support 5 and a Bucky grid 7 provided with 75 rounded edges 8 is arranged to move back and forth upon these rollers. A pair of laterally extending lugs 9 project from the sides ofthe grid 7 and a pair of upstanding pins or lugs 10 are vsecured to the supporting member 5. A coil 8o spring 12 is secured to each of the respective lugs 9 and 10 Vfor the purpose of causing movement of the grid 7 when these springs are tensioned as shown in Fig. 1.

An upwardly extending pin 13 is also rigidly 85- secured to the support 5 and a hand lever 14 is pivotally secured to this latter pin 13. This hand lever 14 is connected at one end to the grid 7 by means of a pivoted link member 15 which moves the grid to one extremity of its movement 90 and places the coil springs 12 under tension when the lever is rotated about its pivot 13. An angularly extending shoulder v16 is rigidly secured to the hand lever 14 and is provided with a small pin 17. A releasable catchklS is pivotally se- 95 cured to a small upwardly extending pin 19 and is positioned to engage the pin 17 carried by the shoulder 16 when the grid is moved by the hand lever 14 to the position shown in Fig. 1. Y A small coil spring 20 maintains the catch 18 100 in engagement with the small pin 17 until disengagement thereof is caused by the operator pulling on a releasing cord or cable 22. Upon disengagement of the catch 18 and the pin 17 the grid 7 will move upon the rollers 6, due to the 105 potential energy stored in the respective springs 12 when the grid waspreviously moved by the hand lever 14, until the hand lever strikes a suitable stop, such as a pin 23.

VIn order to regulate the speed of movement of 110 the grid in response to the action of the springs 12 upon release of the catch 18 I provide a timing mechanism now about to be described.

A bracket 24 is secured to the support 5 and a pair of yieldable chambers 25 and 26, which are essentially metallic bellows, are secured to this bracket on each side thereof. A volume of a suitable non-compressible fluid, such as oil 27, is contained within these chambers which are separated by a wall portion of the bracket 24. The free ends of these yieldable chambers are each provided with a suitable sealing plug 28 and 29, respectively, and a concentric shaft 30 passes through the bracket portion 24 which is threaded into the sealing plug 28 of the cham-. ber 25 and telescopically engages the sealing plug 29 of the chamber 26.

Passages 32 are provided in the separating wall of the bracket 24 for permitting the huid 27 to pass in one direction only, namely, from the chamber 25 to the chamber 26. A check valve 33 surrounds the shaft 30 interiorly of the chambei' 26 and is of a sufficient diameter to close the respective passages 32 when in contact with the wall portion of the bracket 24. A collar 34.

surrounds the shaft 30 and is rigidly secured thereto within the chamber 26 and a spring 35 is disposed between this collar and the check valve 33 for the purposeof closing the passages 32 and preventing the ow of fluid in an opposite direction or from the chamber 26 to the chamber 25.

A cylinder 36 provided with a suitable sealing plug 37 is` disposed adjacent the yieldable chambers and forms a portion of the bracket 24 which supports these chambers. A rotatable valve 38 has a longitudinal passage 39 therein which communicates with a pair of tapering peripherial passages 40 and 42. An adjusting shaft 43 is rigidly secured to the rotatable valve 38 and passes outwardly through the sealing plug A37 to a point exteriorly ofthe support 5 where it is provided with va control knob 44 for operation by theoperator. This shaft 43 is provided with a gear 45 which lengages a similar gear 46k carried bya shaft 47 extending tothe opposite side of the support for the purpose of adjusting the valve 38 from either side of this support 5.

Anangular passage 48 is provided in the wall portion of the bracket 24 which communicates with the yieldable chamber 25 and the tapering peripheral passage 40. A similar angular passage 49 communicates with the chamber 26 and thefother peripherial groove 42 of the valve 38.

In this manner the iiuid 27 flows from the chamber 26, through angular passage '49, peripherial passage 42, longitudinal passage 39 and thence into the chamber 2 5 through peripherial passage 49 and angular passage 48 when the check valve 33 closes the passages 32. During operation of the timing device some 'of the uid will flow through the above mentioned passages in the valve 38 in a direction opposite to that just described from chamber 25 to the other chamber 26. This quantity will be slight, however, due to the majority thereof being permitted to iiow through the passages 32 by release of the check valve 33.

In order toy operably connect the yieldable chambers to the grid 7 I provide a shaft 50 engaging the sealing plug 28 through a threaded connectionrand slidably supported by a suitable bracket 52. The free end of this shaft 50 is provided with a fixed collar 53 and a coil spring 5 4 is disposed upon the shaft between this collar 53 and the bracket 52 for the purpose of causing expansion of the yieldable chamber 25. A laterally extending pin 55 is rigidly secured to the shaft 50 and is engaged by a bifurcated bracket portion 56 carried by the hand lever 14 to cause movement of the shaft 50 and expansion of the chamber 25 against the tension of the spring 54.

The operation of my device is as follows: the hand lever 14 is rotated about its pivot 13 in the direction indicated by the arrow in Figure 2, which moves the grid upon the rollers 6 to the position sho-wn in Figure l, and places the respective coil springs 12 under tension. The catch 18 will then engage the pin 17 carried by the shoulder 16 and maintain the grid in the position shown in Figure 1 until released by the cable 22.

During rotation of the hand lever 14 about its pvot the bifurcated bracket portion 56 which engages the pin 55 will cause movement of the shaft 50 to the right, as viewed from Figure 1, against the tension of the spring 54. This movement of shaft 5 0 causes the yieldable chamber 25 to become compressed and the fluid` 27 to pass through the respective passages 32, due to the opening of the check valve 33, and expand the yieldable chamber 26.

The grid 7 is now in position to move in the iield or" exposure between a source of Xf-rays which lis normally positionedabove the grid a sensitized lm normally below the grid. The

operator then pulls on the cable22 causing disengagement of thecatch 18Y frornthe pin 1 7 al lowing theenergystored in the respective springs 12 to cause movement of the grid before the X'f'iy. tube .(.not Shown). is enelgzfdu ftre' @he required period of exposure the tube is then der energizedand after the expiration of this period movement of the grid ceases.

Upon release ofthe c atchl thehand lever 14 will rotate about its pivotal connection 13 in a clockwise direction of rotation until it contacts the pin 2 3. This motion caused bythe potentialenergy of the respective springs 12 the Spring 54 beine .transmitted t0. the hand 1ev`f .r14 through the link connection 15 and the bifurf cated portiei156 Asthe hand lever thus rotates the shaft 50 will move tdthe left as shown in the iigures by the expanding of the spring; and the transmission of the energy from ,the springs l2 as just stated. Movement therefore of this shaft will cause expansion of the yieldable chamber 25 which had been previously 'come pressed, and compression of the nowtexpanded chamber 26. The suction caused bythe expansion of the chamber 25 together with the coil spring 35 closes the check valve 33 and prevents the fluid 27 from iiowing between the chambers through the passages 32.

The fluid will, however, flow from chamber 26 to chamber 25 through the adjustable "valve the manner previously described with the rate A'of iiow and consequently the speed of mo'viient of the grid 7 dependentupon the setting of the adjustable valve. Assuming it is desired to increase the speed of movement of the grid 7, the control knob 44 is rotated in a clockwise direc"- tion or the control knob secured to the shaft 47 may be rotated in the same direction to increase the o-w of uid and the speed of movement of the grid. Rotation of either of these control knobs causes rotation of the valve 38 and as the respective peripherial passages 40 and 42 are tapered with `the widest portions thereof closer to the longitudinal passage 39 as can be appreciated from Figure l, the ingress and egress of the fluid 27 from the respective'passages 49 and 48 respectively will be increased.

This increase of the rate oi flow of the fluid 27 between the yieldable chambers 26 and 25 thus enables the grid '7 to be moved more rapidly in response to the potential energy of the respective springs l2 and spring 54. In a similar manner should it be desired to decrease the speed of movement of the grid the valve 38 is rotated in a direction opposite to that just mentioned which registers the restricted portions of the passages 40 and 42 With the respective passages 48 and 49 to thus permit the uid 27 to flow less rapidly and the speed of movement of the grid 7 to decrease. Y Y

It can thus be readily seen by those skilled in the art that I have provided a novel timing device for a movable grid employed for suppressing secondary X-rays in which a pair' of yieldable chambers containing a ncn-compressihle fluid and operably connected to the grid are utilized, and in Which the rate or iiow ofthe fluid from one chamber to the other may be regulated to thus adjust the speed of movement of the grid With minute exactitude.

Although I have shown and described one specific embodiment of my invention I do not desire to be limited thereto as various other modications thereof may be made without departing from the spirit and scope of the appended claims.

What is claimed is:

l. In an X-ray device, the combination With a movable grid and means to cause movement thereof, of mechanism for regulating the speed of movement of said grid comprising a plurality of yieldable chambers operably. connected to said grid, a fluid contained in said chambers, means to provide a passage for the flow oi fluid from one of said' yieldable chambers into the other during movementrof said grid, in one direction of its travel, and means to provide a passage for the flow of fluid from one of said yieldable chambers into the other during movement of said grid in its other direction of travel.

2. In an X-ray device, the combination with a movable grid and means to cause movement thereof, of mechanism for regulating the speed of movement of said grid comprising a plurality or yieldable chambers operably connected to said grid, a non-compressible fluid contained in said chambers, means to provide a passage `for the flow of fluid from one of said yieldable cha bers into the other during movement of said grid in one direction, and adjustable means operable to regulate the now of said fluid from of yieldable chambers provided with a fluid therein and operably connected to said grid for restricting the movement thereof in response to the operation ci" said automatic means, means to provide a passage for the iiow of fluid from one of said yieldable chambers to the other upon actuation of said manually operable means, and means associated with said yieldable chambers for regulating the flow oi said iluid from one of said 4chambers into the other to adjust the speed of movement of said grid in response-to the operation of said automatic means.

4. In an X-ray device, a grid for suppressing the passage of secondary X-rays mounted for reciprocatoryV movement, manually` operable means for moving said grid in one direction of its reciprocatory movement, automatic means for causing movement of said grid in the opposite direction oi its reciprocatory movement, a pair of yieldable chambers operably connected to said grid provided With a fluid therein and separated by a Wall having a communicating passage to aliow the lrapid flow of uid from one of said yieldable chambers to the other When said grid is moved in one direction of its reciprocatory movement in response to actuation of said manually operable means, a valve for opening and closing the communicating passage between said yieldable chambers to cause the flow of saidl fluid from one of said yieldable chambers to the other during movement of said grid in onedirection in response to operation of said manually operable means, and an adjustable valve interconnecting saidyieldable chambers for `regulating the iioW or" iiuid from one of said yieldable chambers to the other to vary the speed of movement of said grid in the opposite direction of its reciprocatory movement in response to actuation of said automatic means.

5. In an X-ray device, a grid for suppressing the passage of secondary X-rays mounted for reciprocatory movement, mechanism for moving grid in one direction of its reciprocatory movement, separate means for moving said grid in the opposite direction of movement, a pair ofyieldable chambers provided with a fluid therein, said mechanism connecting said yieldable chambers to said grid to cause one of said yieldable chambers to become compressed and the other to become expanded during movement of said grid in one direction of its reciprocatory movement upon operation of said mechanism and the opposite operation of the respective chambers when said grid is moved in its other direction of movement in response to operation of said means, means interposed between said chambers to allow the rapid flow of said iiuid from one of said chambers into the other during movement of said grid in one direction of movement upon operation of said mechanism and prohibiting the flow of said iiuid during movement of said grid in the opposite direction in response to the operation of said iirst mentioned means and adjustable means interconnecting said yieldable chambers to adjust the flow of said fluid between said chambers and regulate the speed of said grid in one direction of movement in response to operation of said iirst mentioned means.

6. In an X-ray device, a grid for suppressing the passage of secondary X-rays mounted for reciprocatory movement, means for moving said grid in one direction of its reciprocatory movement, separate means for moving said grid in the opposite direction of movement, a pair of yieldable chambers provided with a fluid therein, said first mentioned means connecting said yieldable chambers to said grid to cause one of said yieldable chambers to become compressed and the other to become expanded during movement of said grid in one direction of its reciprocatory movement upon operation or" said rst mentioned means, and the opposite operation of the respective chambers when said grid is moved in its other direction of movement in response to 1 operation of said second mentioned means, a

check valve interposed between said chambers to allow the rapid ow of said fluid from one of said chambers into the other during movement of said grid in one direction of movement upon operation of said rst mentioned means and prohibiting the flow of lsaid uid Aduring movement of said grid in the opposite direction in response to operation of said second mentioned means, and an adjustable valve interconnecting said yeldable chambers to adjust the iiovv of said fluid between said chambers and regulate the speed of said grid in one direction of movement in response to the operation of said second mentioned means.

7. In an X-ray device, a grid .for suppressing the passage of secondary X-rays mounted for reciprocatory movement, a hand lever for moving said grid in one direction of its reciprocatory movement, a releasable catch engageable with said hand lever for maintaining said grid in one extremity of its movement, tensioning means for moving said grid in the opposite Vdirection of movement upon release of said catch, a pair of yieldable chambers containing a .fluid therein and provided with ashaft vinterconnecting said chambers with a portion thereof disposed exteriorly of said chambers, tensioning means carried by said shaft for compressing one of said yieldable chambers and expanding the other, a yoke interconnecting said hand lever and said shaft for storing potential energy in the tensioning means carried by said shaft upon movement of said grid by said hand lever, said grid upon movement thereof by said hand lever causing the storing of -energy in said rst mentioned tensioning means, a valve disposed between said yieldable chambers and operable to provide a passage for the now of uid from one of said yieldable chambers to the other in response to movement of said grid by said hand lever, and a regulating valve to provide a passage for the flow of said fluid and operable to restrict the passage and control the flow of said fluid from the expanded chamber to the compressed chamber thereby controlling the speed or said grid in its opposite direction of movement in response to the action of both of said tensioning means upon release of said catch.

CARL J. LARSEN. 

